The present invention relates in general to insulation concepts for kitchen appliances, such as refrigerators, and in Particular to the insulation design for refrigerator doors.
Refrigerator doors typically include an outer panel whose outer surface is designed for aesthetics and an inner panel which is structured in order to store food and beverage. Between these two panels or surfaces is an insulation layer of a suitable packing or filler. Although not all refrigerator doors are the same, for example, some do not include in-door storage, the basic structure of inner and outer panels separated by insulation is the standard today. Some prior designs have also included openings in the door in order to allow air flow to the insulation. While the present invention includes vent openings which enable air flow through the insulation, the present invention is structurally different from any of the earlier vented designs in a number of important aspects.
The following patent references are representative of refrigerator door designs which typify prior constructions:
______________________________________ Patent No. Patentee Issue Date ______________________________________ 2,553,832 Richard 05/22/1951 2,304,757 Arthur 12/08/1942 3,025,683 Baker et al. 03/20/1962 2,368,837 Hubacker 02/06/1945 2,451,286 Heritage 10/12/1948 4,808,457 Kruck et al. 02/28/1989 2,817,124 Dybvig 12/24/1957 3,078,003 Kesling 02/19/1963 3,307,318 Bauman 03/07/1967 2,939,811 Dillon 06/07/1960 2,863,179 Gaugler 12/09/1958 ______________________________________
Richard discloses a refrigerator door construction which includes a lower freezing chamber door 10 and an upper humidity chamber door 11. The inner panel of each door is provided with a plurality or series of vents. Each door is filled with rock wool insulation and the vents allow air flow into the rock wool insulation in order to remove any moisture from the insulation. The invention focuses on the placement of the vents in order to facilitate circulation of air by convection and on a reduction in the number of vents due to their location. The rock wool insulation is not encased in any type of pouch or enclosure and thus may not be fabricated off-line and later assembled into the door unit at the production line stage. The inner and outer shells of each door are assembled together by a flange and seal combination.
Arthur discloses a refrigerator construction wherein the door or cover 6 includes in its inner wall a single orifice 26 so as to vent the glass wool filled interior of cover 6 into a refrigerating space 8. Arthur is similar to Richard in that the insulation is not encased or arranged in any type of pouch or panel and with only a single opening there is no means to establish air circulation through the insulation. As the Arthur patent indicates, this orifice 26 allows the insulation to breathe.
Baker et al. discloses an air circulation system and structure for a refrigerated cabinet. Air is blown or circulated through the cabinet by means of a blower which is disposed in a passageway in the cabinet door. The flow path is from the passageway initially, through the refrigerated cabinet and then back into the passageway by means of one of several circulatory paths. This device also utilizes a baffle arrangement surrounding the cooling element in the refrigerated cabinet in order to direct the movement of air flowing from the passageway in the door over the cooling elements, thereby affording noticeably cooler circulating air than when a baffle is not used. This particular device does not include any type of vent openings for the free or natural flow of air and moisture from the refrigerated cabinet through the insulation in the door.
Hubacker discloses a refrigerator cabinet construction which includes a hollow housing defined by spaced walls. The walls contain insulating material and the housing is provided with an evaporator for cooling the interior. At least one of the interior walls is formed with a plurality of perforations whereby the evaporator may dehydrate therethrough any moisture that may be contained within the associated spaced walls. This particular structure utilizes a forced circulation by means of the evaporator and as with Richard and with Arthur and Baker et al., the insulation which is present is not in panel form nor in self-contained pouch form.
Heritage discloses a refrigerator construction having means to restrict moisture in the walls of the cabinet. The Heritage disclosure makes reference to concerns over wetting of insulation and discusses the physical properties of wet and dry air and the dehydrating action which occurs in refrigerator operation. This particular device attempts to avoid various defects or problems with earlier refrigerator constructions by constructing the refrigerator door in such a way as to minimize or prevent any pumping action or breathing in and out of air. Another object of the invention is to utilize the dehydrating action of the food compartments in order to impose drying conditions on the insulation by the details of its construction. This particular device does not include any type of presealed or encased insulation pouch, nor are there any vented openings or apertures for a flow-through of air.
Kruck et al. discloses a self-contained thermal insulation panel of generally rectangular form which is suitable for placement within the walls or doors of a refrigerator cabinet. This thermal insulation panel consists of a hermetically sealed envelope surrounding an assembled framework defining a plurality of thin parallel internal cavities. The cavities are formed by a plurality of thin, stretched-out sheets, each preferably with at least one reflective face, spaced apart by thin interlocking peripheral gaskets between a top and a bottom frame member. Although an insulation panel construction is provided by this particular reference, the entire focus is on the details of the construction of the panel which does not include any preconstructed and enclosed pouches of insulation nor is there any indication of a porous or permeable outer skin for the insulation panel so as to allow the natural flow of air and moisture through the encased insulation.
Dybvig discloses a refrigerator apparatus which includes a unitary bag having at least two side-by-side compartments separated from each other by a common imperferate wall or membrane and charging one of the compartments with an insulating filler material and a gas of low heat conductivity and hermetically sealing the same, and encasing in the other compartment a cushion or layer of compressible insulation material. The outer wall of the gas-filled compartment and the inner wall or membrane of that compartment are formed of a material impervious to the passage of any insulating gas, air or moisture while the outer wall of the other compartment is Preferably substantially impervious to the passage of moisture therethrough, but is sufficiently pervious to the passage of air in order to permit the compartment to breathe in order to equalize the pressure between the latter compartment and the atmosphere. Although this particular apparatus appears to focus more on the specific construction of the insulation compartments, including the characteristics of the encasing skin and the specifics of the construction, there is little or no attention given to how this particular insulation panel may be adapted to current refrigerator door designs such as by providing vent openings in the inner panel of the door. Although the outer wall 12 is formed of a moisture impervious material such as polyethylene having one or more pin holes or breather openings as indicated at 13, there is no indication of utilizing this panel in a refrigerator door nor in providing vent openings in that door in order to create a natural flow of air from the interior of the refrigerator through the insulation of the door.
Kesling discloses a refrigerator cabinet construction which focuses specifically on the insulation panel but does not indicate any intent in the design of that panel to create a flow loop for air and moisture from the cabinet interior through the insulation of the door. As has previously been commented upon, the insulation of this particular construction simply appears to be foamed or filled insulation between two panels and is not a separately constructed insulation panel.
Bauman discloses a foam plastic filler method which may be utilized in the door and side walls of a refrigerator and pertains specifically to a method for filling void spaces with synthetic plastic foam utilizing a sealed bag of compressed synthetic plastic foam and placing this sealed bag in an insulating spaced wall for filling cracks and voids. Initially a bag of insulation is prepared and sealed and air is expelled from the bag by the application of a vacuum. The external atmospheric pressure maintains the foam in a compressed state and only when the bag is opened or punctured to allow the entry of air will the foam reexpand to its normal volume, after the sealed bag has been placed in a useful position such as in a joint or between spaced walls. Certain benefits can result by using the compressed foam package, releasing the vacuum once in place so that it will act to completely fill the void.
Dillon discloses a heat insulating unit for refrigerator cabinets including a heat-insulating unit of deformable pillow-like construction which is adapted to be conformed to the space disposed between the inner and outer metal walls of a refrigerator cabinet or the like. The unit includes a hermetically sealed bag having deformable sheet-like walls of low thermoconductivity that are highly impervious to gas. The sealed bag contains both a deformable mass of porous solid heat-insulating material and a charge of gas at substantially atmospheric pressure. The charge of gas is of a thermoconductivity lower than that of air and essentially comprises a mixture of carbon dioxide and dichloride difluoromethane. There is no attention given in this particular reference to any type of vented structure for the natural flow of air and moisture through the refrigerator cabinet and through the door insulation.
Gaugler discloses a refrigerating apparatus where the top and side walls are insulated and the insulation panel or construction is of a bag-like design including an outer protective bag within which there is disposed a layer of compressible insulation and an inner gas-filled hermetically sealed bag containing fibrous insulation. As can readily be noted, this reference focuses specifically on the varying insulation concepts and characteristics and does not direct its attention at all to how this insulation may be placed in a refrigerator door with a porous or permeable outer skin in combination with door vent openings for the natural flow of air through the encased door insulation.
With the exception of Richard and Arthur, which do provide some type of vent or orifice through the refrigerator door panel into the door insulation, the remaining references listed above employ insulation concepts in combination with some type of appliance or cabinet where the interior and exterior panels are solid. The enclosed insulation is sealed inbetween these two panels and is isolated from the outside atmosphere and from any air or moisture flow communication. One effect of this isolation and the lack of any air or moisture flow through the insulation is to allow condensation and ice buildup in the insulation. When such condensation and ice buildup occurs, the insulating value of the door insulation is reduced thus making the overall refrigerator operation less efficient.
The present invention provides a solution to the aforementioned deficiencies of typical or conventional refrigerator door designs by providing vent holes in the inside refrigerator door panel. By means of these vent holes, a natural flow path for air and moisture is provided from the interior of the refrigerator through the door insulation. The flow prevents condensation and ice buildup in the encased door insulation. As a result, the insulating value remains as originally designed and the designed or intended efficiency is not lessened.
With regard to the Arthur reference, there is a single orifice provided but the insulation panel is not really a panel and not a self-contained unit. Rather, the insulation which is placed in the door is either loosely arranged discrete particle insulation or may be foamed in place. Whatever the particular method to get the insulation material properly arranged in the door, there are a number of manufacturing inefficiencies and problems. If loose discrete particulate insulation is utilized, then a great deal of care must be taken so as to arrange it uniformly and to avoid any shifting or compacting so that the insulating characteristics throughout are uniform. There are also significant concerns over handling and the health risks due to air-borne particulate. There is very little served by an insulation design for a refrigerator cabinet if the insulation across the entire surface area of the door is not uniform. If foam-in-place insulation is used for the insulation in the door, then there may not be a suitable cell structure for the insulation or insulation density in order to allow an adequate flow through of air to prevent the buildup of ice or condensation. The release of fluorocarbons by such foam insulation also presents a substantial health risk and environmental hazard. Another concern with the Arthur structure is that there is but a single orifice and thus it is difficult to envision how any type of realistic flow pattern could be achieved so as to maintain the entirety of the encased insulation material free of any condensation or ice buildup. A great number of advantages are believed to be provided by the present invention not only by its encased insulation panel which may be assembled off-line under better-controlled and safer conditions and then assembled within the inner and outer panels of the door, but the specific design of two series of vent openings in the inner door panel enables a flow-through design.
With regard to the Richard disclosure, it includes the same deficiencies as Arthur as to the design of an insulation panel. The Richard insulation is rock wool and must be handled, arranged and packed into outer shell 22 at the time of door assembly. This insulation is not pre-packaged in any type of pouch or envelope to facilitate handling, usage and assembly. Since Richard does not disclose a Panel but rather simply loose insulation which is arranged between an inner and outer wall, the same concerns as in Arthur as to the uniformity of the insulation arrangement, its density and the ability for an adequate flow through are all present.